Psychopharmacology

, Volume 137, Issue 3, pp 292–302

Discriminative stimulus properties of mCPP: evidence for a 5-HT2C receptor mode of action

  • J. Gommans
  • Theo H. Hijzen
  • Robert A. A. Maes
  • Berend Olivier
ORIGINAL INVESTIGATION

DOI: 10.1007/s002130050622

Cite this article as:
Gommans, J., Hijzen, T., Maes, R. et al. Psychopharmacology (1998) 137: 292. doi:10.1007/s002130050622

Abstract

Previous drug discrimination studies with the serotonergic drug m-chlorophenylpiperazine (mCPP) showed conflicting results, with some authors concluding that the cue was mediated by 5-HT2C receptors, but others that it was definitively not. We further examined the discriminative stimulus properties of mCPP in rats and reviewed previously published data. We trained rats to discriminate mCPP (2.0 mg/kg, PO) from water. We found that the mCPP cue generalized to m-trifluoromethyl-phenylpiperazine (TFMPP) and 6-chloro-2-(1-piperazinyl)-pyrazine (MK-212), and partially to eltoprazine, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), fenfluramine and trazodone. A moderate level of generalization was obtained with quipazine, 1-(m-chlorophenyl)biguanide and clonidine. No generalization was found with flesinoxan, methiothepin, idazoxan and haloperidol. Mianserin and methysergide antagonized the mCPP stimulus, whereas ketanserin antagonized it partially. Metergoline, methiothepin and clozapine only marginally antagonized the mCPP stimulus. These results show that the discriminative stimulus effects of mCPP are predominantly mediated by 5-HT2C receptors, and to some extent by 5-HT1B receptors. When considering our results and other research together, the substitution tests clearly point to a 5-HT2C receptor mediated stimulus, with an additional role for 5-HT1B receptors. Antagonism studies are less clearcut, but are also suggestive of a 5-HT2C receptor mediated effect. A definitive answer as to whether other receptors, e.g. 5-HT2B and 5-HT7, are of any importance in mCPP’s discriminative stimulus properties has to wait for more selective ligands.

Key words mCPP (m-chlorophenylpiperazine)Drug discrimination5-HT2CRat

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • J. Gommans
    • 1
  • Theo H. Hijzen
    • 1
  • Robert A. A. Maes
    • 2
  • Berend Olivier
    • 1
  1. 1.Department of Psychopharmacology, Faculty of Pharmacy, Universiteit Utrecht, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands e-mail: J.Gommans@FAR.RUU.NL, Fax: + 31-30-253-7387NL
  2. 2.Department of Toxicology, Faculty of Pharmacy, Universiteit Utrecht, Sorbonnelaan 16, 3584 CA Utrecht, The NetherlandsNL